package demo2;
//Computer类
public class Computer {
    public void Open(){
        System.out.println("打开电脑");
    }

    public void Close(){
        System.out.println("关闭电脑");
    }

    public void useDevice(USB usb){
        usb.openDevice();
        if(usb instanceof Mouse ){
            Mouse mouse=(Mouse) usb;
            mouse.click();
        }
        usb.closeDevice();
    }
}
